This invention relates to the art of sleeving fluid carrying conductors. It has particular relationship to the sleeving of the corroded or damaged conductors which carry the coolant; i.e. the primary conductors, of the steam generator of a nuclear reactor plant.
To repair the corroded coolant conductors of a steam generator, sleeves are inserted into the conductors. The sleeves are of different lengths, typically 27, 30, 36 or 44 inches. The lower end of each sleeve is coincident with the lower end of the coolant conductor in which it is inserted. A sleeve, once inserted, is expanded typically near its upper end and near its lower end in a region within the tube sheet. After being expanded the sleeve is rolled in the top and bottom regions so that a mechanical joint is formed between the sleeve and the conductor. Typically a sleeve is rolled over a length of about 21/8" at the lower end and 11/2" at the upper end. Each joint formed by the rolling should be capable of effectively resisting the penetration between the outer surface of the sleeve and the inner surface of the corroded or damaged coolant conductor, of the high pressure coolant, which will flow through the sleeve and through the coolant conductor beyond the sleeve. This invention concerns itself with the rolling of the top and bottom of the sleeve; i.e., the upper end of the sleeve and the part of the sleeve in the tube sheet.
Access to the coolant conductor for rolling of the sleeve is available through the channel head of the steam generator. The environment within the channel head is radioactive so that the time within which personnel may work therein is limited, typically 15 to 45 minutes. After an exposure within a channel head, exposed personnel cannot enter a radioactive environment for several months. Apparatus which is used within a radioactive channel head also becomes radioactively contaminated. In addition the channel head is composed of metal and use of apparatus which requires electrical voltages exceeding about 30 volts within the channel head is prohibited to avoid hazards of electrical shocks to personnel.
In accordance with the teachings of the prior art the rolling was carried out wih a hand tool. This tool included a tube having extendable rolls, sometimes referred to herein, as roller means, in a region thereof. Within the tube a tapered mandrel was provided. The tapered mandrel could be moved by hand axially into the tube to press the rolls into rolling engagement with the sleeve. The mandrel was rotatable by an air motor. As the operator started pressing the mandrel into the tube he started the motor so that the mandrel rotated, rotating the rolls while the mandrel was entering the tube. After the rolling was completed the tube and mandrel were removed from the sleeve.
This prior art rolling operation was difficult to carry out and time consuming. If one operator could not carry out the complete rolling in the alloted exposure time, it was necessary to replace him with another operator.
It is an object of this invention to overcome the disadvantages and drawbacks of the prior art in the rolling of sleeves in fluid conductors in a hostile environment and to provide rolling apparatus or roller tools, which shall be remotely automatically actuable, for carrying out a complete rolling operation with minimal intervention of personnel.